This invention relates to a process for the catalytic hydration of olefins to provide alcohols, ethers or their mixtures. More particularly, the invention relates to a process for the hydration of light olefins such as ethylene, propylene, butenes, pentenes, hexenes, heptenes, etc., and their mixtures to provide alcohols and/or ethers employing the acidic form of the synthetic porous crystalline material, or zeolite, MCM-22 as catalyst. The alcohols and/or ethers are useful, inter alia, as high octane blending stocks for gasoline.
There is a need for an efficient catalytic process to manufacture alcohols and ethers from light olefins thereby augmenting the supply of high octane blending stocks for gasoline. Lower molecular weight alcohols and ethers such as isopropyl alcohol (IPA) and diisopropyl ether (DIPE) are in the gasoline boiling range and are known to have a high blending octane number. In addition, by-product propylene from which IPA and DIPE can be made is usually available in a fuels refinery. The petrochemicals industry also produces mixtures of light olefin streams in the C.sub.2 to C.sub.7 molecular weight range and the conversion of such streams or fractions thereof to alcohols and/or ethers can also provide products useful as solvents and as blending stocks for gasoline.
The catalytic hydration of olefins to provide alcohols and ethers is a well-established art and is of significant commercial importance. Representative olefin hydration processes are disclosed in U.S. Pat. Nos. 2,162,913; 2,477,380; 2,797,247; 3,798,097; 2,805,260; 2,830,090; 2,861,045; 2,891,999; 3,006,970; 3,198,752; 3,810,849; and, 3,989,762, among others.
Olefin hydration employing zeolite catalysts is known. As disclosed in U.S. Pat. No. 4,214,107, lower olefins, in particular, propylene, are catalytically hydrated over a crystalline aluminosilicate zeolite catalyst having a silica to alumina ratio of at least 12 and a Constraint Index of from 1 to 12, e.g., HZSM-5 type zeolite, to provide the corresponding alcohol, essentially free of ether and hydrocarbon by-product.
According to U.S. Pat. No. 4,499,313, an olefin is hydrated to the corresponding alcohol in the presence of hydrogen-type mordenite or hydrogen-type zeolite Y each having a silica-alumina molar ratio of 20 to 500. The use of such a catalyst is said to result in higher yields of alcohol than olefin hydration processes which employ conventional solid acid catalysts. Use of the catalyst is said to offer the advantage over ion-exchange type olefin hydration catalysts of not being restricted by the hydration temperature. Reaction conditions employed in the process include a temperature of from 50.degree.-300.degree. C., preferably 100.degree.-250.degree. C., a pressure of 5 to 200 kg/cm.sup.2 to maintain liquid phase or gas-liquid multi-phase conditions and a mole ratio of water to olefin of from 1 to 20. The reaction time can be 20 minutes to 20 hours when operating batchwise and the liquid hourly space velocity (LHSV) is usually 0.1 to 10 in the case of continuous operation.
U.S. Pat. No. 4,611,086 describes the hydration of olefins to provide aliphatic alcohols employing natural or synthetic offretite as catalyst.
European Patent Application 210,793 describes an olefin hydration process employing a medium pore zeolite as hydration catalyst. Specific catalysts mentioned are Theta-1, said to be preferred, ferrierite, ZSM-22, ZSM-23 and NU-10.
Japanese laid-open application 60-246,335 describes the hydration of branched olefins in the presence of finely powdered zeolite catalyst.